Question 1

Which of the following best describes the structure and location of a typical bacterial chromosome compared to a eukaryotic chromosome?

Accepted Answer

Bacterial chromosomes are circular, found in the nucleoid region, and not associated with histones.

Question 2

Which of the following statements about plasmids is CORRECT?

Accepted Answer

Plasmids are small, circular DNA molecules that replicate independently of the bacterial chromosome and often carry genes for antibiotic resistance.

Question 3

During DNA replication in bacteria, which enzyme is responsible for joining Okazaki fragments on the lagging strand?

Accepted Answer

DNA ligase

Question 4

If a DNA strand has the sequence 5'-ATGCCGTA-3', what is the sequence of the complementary DNA strand?

Accepted Answer

3'-TACGGCAT-5'

Question 5

Which of the following best describes the central dogma of genetics?

Accepted Answer

DNA is transcribed into RNA, which is then translated into protein.

Question 6

Which of the following statements about the lac operon is TRUE?

Accepted Answer

The lac operon is induced when lactose is present and glucose is absent.

Question 7

A point mutation that results in a premature stop codon is called:

Accepted Answer

Nonsense mutation

Question 8

Which of the following best describes conjugation in bacteria?

Accepted Answer

Direct transfer of DNA through a pilus from an F+ donor to an F- recipient.

Question 9

Which of the following physical methods is used to preserve, rather than kill, microbes?

Accepted Answer

Lyophilization

Question 10

Which of the following is a beta-lactam antibiotic, and what is its primary mode of action?

Accepted Answer

Penicillin; inhibits cell wall synthesis by preventing cross-linking of peptidoglycan

Question 11

Which of the following best explains why broad-spectrum antibiotics can lead to secondary infections such as Clostridioides difficile?

Accepted Answer

They kill beneficial normal microbiota, reducing microbial antagonism and allowing opportunistic pathogens to grow.

Question 12

Which of the following is a mechanism by which bacteria can develop resistance to antimicrobial drugs?

Accepted Answer

Producing enzymes such as beta-lactamase that inactivate the drug

Question 13

Which of the following statements about viruses is CORRECT?

Accepted Answer

Viruses are acellular, lack ribosomes, and require a host cell for replication.

Question 14

Which of the following best describes the difference between a virus in the extracellular state and the intracellular state?

Accepted Answer

Extracellular viruses are called virions and possess a capsid; intracellular viruses exist as nucleic acid only.

Question 15

Which of the following is the correct sequence of events in the lytic replication cycle of a bacteriophage?

Accepted Answer

Attachment, entry, synthesis, assembly, release

Question 16

Which of the following statements about prions is TRUE?

Accepted Answer

Prions are infectious proteins that cause diseases by inducing misfolding of normal cellular proteins.

Question 17

Which of the following antimicrobial methods is most effective at destroying prions?

Accepted Answer

Incineration

Question 18

Which of the following best describes the function of tRNA during translation?

Accepted Answer

tRNA carries amino acids to the ribosome and matches its anticodon to the codon on mRNA.

Question 19

Which of the following is a key difference between inducible and repressible operons?

Accepted Answer

Inducible operons are usually off and can be turned on by an inducer; repressible operons are usually on and can be turned off by a corepressor.

Comprehensive Microbiology Study Guide: Genetics, Microbial Control, Antimicrobials, and Viruses

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